HAVANA (AP) — Silently and without pause, the giant African snail has been invading Cuba.

The snails with brilliantly striped shells and bodies up to 8 inches (20 centimeters) long have become public enemy No. 1 for epidemiologists in Cuba. And citizens have grown to fear their ability to transmit diseases and harm crops.

Some families are keeping children indoors to play due to the danger of infection from the snails, which can transmit a potentially severe brain infection called meningoencephalitis and an abdominal disease known as angiostrongiliasis.

They were first detected in Cuba in 2014 and now be found throughout Havana and in almost every one of the island’s provinces. It’s not known how the snail arrived in the nation.